Among the conventionally-known rear vehicle body structures are ones where left and right side sills extend in a front-rear direction of the vehicle body, front floor frames are located inwardly of and extend in parallel to the side sills, and rear frames extend rearwardly from rear end portions of the side sills. In some of the known rear vehicle body structures, front and rear cross members etc. span between the left and right side sills to reinforce the side sills etc.
One example of such rear vehicle body structures is disclosed in Japanese Patent Publication No. 3528644, where the front floor frames are connected with the rear frames. More specifically, the rear vehicle body structure disclosed in the 3528644 publication includes: the left and right side sills extending in the front-rear direction of the vehicle body; the front floor frames located inwardly of and extend in parallel to the side sills; the rear frames extending rearwardly from rear end portions of the side sills; the front and rear cross members spanning between respective front end portions of the rear frames and between respective rear end portions of the front floor frames in a width direction of the vehicle; and reinforcing members each interconnecting the rear cross member and a central portion of the corresponding rear frame.
Because the reinforcing members are each connected to the rear end portion of the corresponding front floor frame, the rear vehicle body structure disclosed in the 3528644 publication would present the problem that, at the time of a rear-end collision, a collapsing load acts only on the rear end portions of the front floor frames so that the collapsing load can not be efficiently transmitted to and along the front floor frames. Further, in the rear vehicle body structure disclosed in the 3528644 publication, the reinforcing members connected in the aforementioned manner each extend diagonally downward from the corresponding rear frame to the rear end portion of the corresponding front floor frame as viewed in a side elevation; for this reason too, the collapsing load produced at the time of the rear-end collision can not be efficiently transmitted to and along the front floor frames.